One technique for expansion of tubulars or screen downhole has involved the use of a swage attached to a hydraulic expansion tool. A hydraulically actuated anchor is disposed above the expansion tool. Application of fluid pressure sets the anchor and causes the expansion tool to stroke. At the end of the stroke, the pressure is removed and the anchor releases. At this time, more pipe has to be added at the surface to allow the anchor to move down and re-cock the expansion tool by letting its body move downwardly back over the segment that had previously been telescoped out to initiate the expansion. Pressure is then re-applied and the cycle starts again as another stroke of the expansion tool sends the swage forward for continuing expansion. Many times hundreds, and in some cases even thousands, of feet of tubular or screen have had to be expanded in such a step-wise manner.
The disadvantage of this method is that it is very time consuming to undo the surface assembly each time another stand of pipe needs to be added to further stroke the expansion tool downhole. The addition of stands of pipe required rig down of the pumping equipment each time, followed by a re-connection of the same equipment to let the expansion process continue.
The present invention seeks to optimize this process. It provides for drill collars or other weights above the anchor, to urge it to go downhole after it is released. This feature is particularly useful in horizontal sections in a wellbore. Additionally, a stinger pipe is run into the drill collars so that when the anchor is released, the assembly rides down but remains in sealed contact with the surface pumping equipment. In this manner the expansion can be carried out continuously by application and removal of pressure, with the collars re-cocking the expansion tool automatically as fluid pressure is removed, following a stroke. A provision is made to hold the stinger to the anchor for initial delivery to the expansion location and for simple disconnects preferably using a J-slot assembly.
In an alternative embodiment, the stinger assembly is replaced with a coiled tubing unit. The collars allow the expansion tool to advance when the anchor is released by simply unreeling additional coiled tubing into the wellbore to allow the expansion tool to re-cock. These and other advantages of the present invention will be more apparent to those skilled in the art by a review of the description of the preferred embodiment below as well as the claims.
A few known expansion devices for tubulars are illustrated in U.S. Pat. Nos. 3,358,760 and 6,012,523.